Polyoxetanes which can be used in peptide synthesis

ABSTRACT

1. A POLYOXETANE WHICH CONSISTS ESSENTIALLY OF A PLURALITY OF UNITS OF THE FORMULA:   -CH2-C(-CH2-X1)(-CH2-O-AR-CH2-X2)-CH2-O- (I) AND   -CH2-C(-CH2-X1)2-CH2-O- (II)   AND, OPTIONALLY, OF UNITS OF AT LEAST ONE OF THE FORMULAE-   -CH2-C(-CH2-X1)(-CH2-O-AR&#39;&#39;)-CH2-O- (III)   -CH2-C(-CH2-Y1)2-CH2-O- (IV) AND   -CH2-C(-CH2-Y)(-CH2-O-)-CH2-O-AR-CH2-AR-O-CH2-C(-CH2-Y)   (-CH2-)-CH2-O-   IN WHICH: EACH OF X1 AND X2 WHICH MAY BE IDENTICAL OR DIFFERENT, REPRESENTS A CHLORINE, OR BROMINE ATOM, Y IS AS DEFINED UNDER X1 OR REPRESENTS A RADICAL OF FORFERENT, REPRESENTS A -O-AR-CH2X2 OR -O-AR&#39;&#39;, EACH OF THE Y1 RADICALS, WHICH MAY BE IDENTICAL OR DIFFERENT REPRESENTS A -O-AR&#39;&#39; OR -O-AR-CH2X2 RADICAL, AR REPRESENTS A DIVALENT AROMATIC RADICAL, THE TWO FREE VALENCIES OF WHICH ARE CARRIED BY CARBON ATOMS OF ONE OR TWO AROMATIC BENZENE RINGS, AND AR&#39;&#39; REPRESENTS THE RADICAL -ARH THE UNITS (I) TO (V) BEING CONNECTED TO ONE ANOTHER VIA THE OXYGEN ATOM WITH A FREE VALENCY OF ONE OF THE UNITS AND A METHYLENE GROUP WITH A FREE VALENCY OF THE ADJACENT UNIT.

"United States Patent C 3,847,868 POLYOXETANES WHICH CAN BE USED INPEPTIDE SYNTHESIS Jean Bouchaudon, Essonne, Guy Bourat, Hauts-de-Seine,and Rodolphe Margrafi, Essonne, France, assignors to Rhone-Poulenc S.A.,Paris, France No Drawing. Filed Feb. 23, 1973, Ser. No. 335,177 Claimspriority, application France, Feb. 28, 1972, 7206696 Int. Cl. C08g 23/04US. Cl. 260-47 R 9 Claims ABSTRACT OF THE DISCLOSURE Polyoxetanes areprovided which consist essentially of a plurality of units of theformula:

in which:

each of X and X which may be identical or different, represents achlorine or bromine atom, Y is as defined under X or represents aradical of formula each of the Y radicals, which may be identical ordifferent, represents a -O--Ar' or -OArCH X radical,

Ar represents a divalent aromatic radical, the two free valencies ofwhich are carried by carbon atoms of one or two aromatic benzene rings,and

Ar represents the radical ArH,

the units (1) to (V) being connected to one another via the oxygen atomwith a free valency of one of the units and a methylene group with afree valency of the adjacent unit. These polyoxetanes, by reason of thefact that they swell very well in, for example, methylene chloride, areparticularly suitable for use as the support in the preparation ofpeptides using solid phase synthesis.

The present invention relates to polyoxetanes which can be used as asubstratum polymer for the synthesis of polypeptides.

According to the present invention there is provided a polyoxetane whichcomprises a plurality of units of the formula:

Patented Nov. 12, 1974 and GH X

-CHz-O CHzXr (II) and, optionally, of units of at least one of theformulae:

CHgX

-CH2 CH2O- CHz-O-Ar' CH2Y| '-CH2- CH2O- HzY1 (III) In these variousunits, the symbols may vary from one unit to the next. These symbols aredefined as follows:

X and X represent a chlorine or bromine atom, Y represents X or aradical of formula:

each of the Y radicals represents a OAr' radical or a --OAr-CH Xradical,

Ar represents a divalent aromatic radical, the two free valencies ofwhich are carried by carbon atoms belonging to one or two aromaticbenzene rings, and

Ar is the radical -ArH.

The linking of the units (-1) to (V) takes place between an oxygen atomwith a free valency of one of the units and a methylene group with afree valency of an adjacent unit.

-Aris, more particularly, a radical of the formula:

in which each of the a radicals, which may be identical or different,represents a hydrogen atom or a linear or branched alkyl, alkoxy or acylradical, these radicals having generally less than 7 carbon atoms, or anitro or nitrile group or a halogen atom, preferably chlorine orbromine, it being possible for at most half of the symbols a to have ameaning other than H, alkyl, alkoxy or acyl.

More specifically, as radicals Ar and Ar, there may be mentionedradicals such that H-ArOH and ArOH represent mera-nitrophenol, oorm-bromophenol, guaiacol, oand m-cresol, or m-isobutylphenol, 0 orm-isopropylphenol, a xylenol, oor mchlorophenol, thymol or phenolitself.

The proportions of the various units are generally such that the numberof ArCH X groups, expressed in milliequivalents (meq.) per gram of drypolymer, is between 0.5 and 4, and preferably between 1 and 3; thepercentage by number of CH OAr groups (including the OH OAr groups,which are merely (VIII) in which Ar' is as defined above and Yrepresents a chlorine or bromine atom or a OAr' radical.

The halomethylation of the intermediate aryloxylated polyoxetanes can becarried out in a conventional manner for halomethylating aromatic rings,it being possible for the intermediate aryloxylated polyoxetane to be inthe form of, for example, granules, shavings, a powder or a film whichmay optionally be screen-reinforced.

Suitable halomethylating agents are well known to those skilled in theart; they include methyl chloromethyl ether (also calledmonochloromethyl ether), ethyl chloromethyl ether and methyl bromomethylether, it being possible to prepare some of these ethers in situ, forexample by reacting formaldehyde with hydrochloric or hydrobromic acid.

The halomethylation is generally carried out in the presence of acatalyst; for this purpose, Friedel-Crafts catalysts such as aluminumchloride, zinc chloride, antimony pentachloride, titanium tetrachloride,boron trifiuoride or, preferably, tin tetrachloride can be employed.

The reaction temperature can vary within wide limits;

it is usually between and +50 C., and preferably between +10 and +30 C.The reaction is preferably carried out at atmospheric pressure, but itis also possible to work at higher or lower pressures. Thehalomethylation can take place with a halomethylating medium in theliquid phase or in the vapour phase. When the halomethylating medium isin the liquid phase, it is possible to carry out the reaction with orwithout a diluent. A liquid which is miscible with the reagents but isinert under the working conditions, for example an alkyl ether such asdi-ethyl ether, is suitable as a diluent. It is generally preferred tocarry out the reaction in the liquid phase, with a diluent and atatmospheric pressure.

The halomethylation reaction can be continued until the desiredproportion of halomethyl groups have been attached to an aromatic ring;the reaction conditions, especially the temperature and the duration ofthe reaction, to be employed can, of course, be determined easily ineach case by simple experiment. It should be noted that halomethylationof the units (VIII) can produce not only units such as (I) and (IV) withY representing but also a certain degree of crosslinking as a result ofsecondary reactions, creating units (V). It should also be noted that,under the specified working conditions, halomethylation of the units(VIII) generally results in only one halomethyl group becoming attachedper Ar group undergoing reaction. It is however also possible for someAr groups to be substituted by more than one halomethyl group. It isbelieved, however, that the proportion of the polyhalomethylated Argroups is relatively small and, for the purpose of simplification, suchunits have been excluded from the units given as forming the polymers ofthis invention, only average units being indicated. It is to beunderstood, however, that the presence of such units is not excludedfrom the polyoxetane of this invention i.e. some of the ArCH X groupscan be in the form -AI'(CH2X2)2.

The intermediate aryloxylated polyethers are prepared advantageouslyfrom poly 3,3-bis (halomethyl)oxetane (hereafter called PBMO) byreplacing the halogen atoms by aryloxy radicals. This substitution,hereafter called aryloxylation, can be carried out easily by reactingPBMO with an alkali metal phenate of the formula Ar'-OM, M being analkali metal and preferably sodium or potassium, in an aprotic polarsolvent, such as dimethylsulphoxide (DMSO), hexamethylphosphotriamide(HMPT), sulpholane, dimethylformamide, dimethylacetamide andtetramethylurea. The phenates which are derived from the phenols of theformula HAr-OH mentioned above are particularly suitable.

The starting PBMO generally has a molecular weight between 50,000 and1,000,000, and preferably between 100,000 and 500,000.

The relative proportion of the reagents to be employed in order toachieve a particular proportion of aryloxy groups in the treated PBMO ispreferably chosen by assuming quantitative yield during thisaryloxylation; this is why the number of mols of phenate employed isusually between 1 and preferably between 20 and 50%, of the number ofhalomethyl groups present in the PBMO used.

The PBMO is employed at concentrations which are generally between 0.5and 20% by weight, and preferably between 1 and 10%.

The temperature of the aryloxylation reaction is usually between 50 and230 C., and preferably between and 200 C. Of course, if a solvent whichis unstable or volatile at high temperatures is used, the reactionshould then be carried out, respectively, at a temperature below thedecomposition temperature or at a pressure which is sufficient to keepthe solvent in the liquid state.

The present invention also provides a process for the preparation of apeptide on a solid support in which the support (or substratum)consists, wholly or partially, of a polyoxetane according to theinvention.

The technique of synthesising peptides on a solid support is known assolid phase synthesis. Such a technique has been described, for example,in Advances in Enzymology, Robert B. Merrifield, 32, 221-296 (1969) andin French specification No. 2,021,591. According to this technique anaminoacid possessing a protected amino group is attached to a gel of anitrochloromethylated or chloromethylated polystyrene copolymercrosslinked with approximately 2% of divinyl-benzene, by carrying outthe reaction according to the following equation:

in which Res represents the base resin (or substratum), Q represents thegroup which protects the amine of the aminoacid, for example, abenzyloxycarbonyl or t-butoxycarbonyl group, and R represents the sidechain of the first aminoacid.

After reaction, the protective group Q is removed and the next aminoacid unit is added in accordance with the techniques used in peptidesynthesis:

R J; l CsH11N=C=NCaH 1 ReS-CHzOCO HNHz QNHCHCOOH i Ilia Res-CHzO C OCHNHC O CH-NHQ In this equation, R represents the side chain of thesecond aminoacid and the other symbols are as defined above. The secondstage is then repeated with a third blocked aminoacid and so on untilthe desired polypeptide structure is obtained. Finally, the completepolypeptide is isolated from the resin by ester hydrolysis techniqueswhich do not affect the peptide bonds, for example by using hydrazine.

Amongst the properties which the substratum must possess are,simultaneously, insolubility in water and in the majority of organicsolvents and a considerable capacity for swelling in certain organicsolvents such as chloroform, dioxane and, especially methylene chloride.Since this swelling makes it easy for the reagents to reach the activesites of the substratum.

The polyoxetanes according to this invention are particularly useful asthe substratum in such a synthesis of polypeptides precisely because oftheir excellent capacity for swelling in methylene chloride. Thiscapacity for swelling is generally greater than that of the polymers orresins derived from polystyrene. Moreover, the -OAr-- groups assist thereactions for attaching aminoacids to the substratum; the use of Arradicals substituted, for example, by nitro groups, also makes itpossible to influence the labile nature of the bond between thesubstratum and the first aminoacid.

Because of the way in which they are prepared, the polyoxetanesaccording to the invention form a very good homogeneous material,especially from the point of view of the distribution of the mobilehalogen atoms i.e. the halogen atoms of the halomethyl groups which arebonded exclusively to an aromatic radical and not to an aliphatic carbonatom.

The polyoxetanes according to the invention can also be used for theproduction of membranes. In the form of a membrane, particularly as acontinuous strip, they make it possible to synthesise polypeptidescontinuously and automatically by successively passing the strip throughbaths of solvents or reagents: this technique advantageously replacesthe known automatic techniques for solid phase synthesis which requirespassing numerous solutions over a bed of resin with, preferably, use ofcombined feed and central remote control systems (see for example,United States Pat, No. 3,531,258).

The membranes based on polyoxetanes according to the invention may, ifdesired, be screen-reinforced, the term screen denoting a reinforcingsupport. For synthesising polypeptides, it is preferred to usescreen-reinforced membranes and, more especially, membranes which havebeen screen-reinforced with materials which are chemically inert towardshalomethyl groups and are also chemically inert under the conditions ofthe peptide synthesis. The use of paper-like materials, for examplepolytetrafluoroethylene papers and glass fibre papers, as a screen makesit possible to stabilise the longitudinal or transverse dimensions ofthe membranes more effectively. The membranes according to the inventionmake it possible to obtain polypeptides having improved purity.

The production of screen-reinforced membranes is advantageously carriedout by coating the screen with a solution of intermediate aryloxylatedpolymer, the halomethylation being carried out subsequently on the filmthus produced. The term coating is used to denote, in general terms,bringing the screen into contact with a solution of intermediatearyloxylated polyoxetane followed by evaporating the solvent;impregnation or pouring can thus be used. The concentration of thesolutions used naturally depends on the solvent; by carrying out severalcoatings, it is possible to attach variable amounts of polyoxetane tothe screen. According to a preferred method for producingscreen-reinforced membranes, coating is continued until the proportionof polyoxetane in the membrane is between 5 and and preferably between20 and 70% The halomethylation can then be carried out on the film underthe same conditions as described above for the aryloxylated polyoxetanealone.

The following Examples further illustrate the present invention.

It has not been possible to measure the degree of crosslinking in allthese Examples (accuracy of the measurements: 1%); the term membrane hasbeen reserved for the products consisting of a screen coated with thepolyoxetanes according to the invention; the products consisting of ascreen coated with intermediate aryloxylated polymer are called films.

The mobile chlorine atoms were measured by (a) heating the sample underreflux for 3 hours in excess of a 5% solution of triethylamine inethanol, followed by (b) determination of the attached nitrogen.

EXAMPLE 1 (A) Potassium phenate.

58 g. of phenol are reacted, at ambient temperature (2025 C.), with 300cm. of a 2 M solution of potassium methylate in methanol, and then themethanol is evaporated.

(B) Preparation of the intermediate phenoxylated polyoxetane.

The phena'te is redissolved in 0.5 l. of dimethylsulphoxide (DMSO) at C.This solution is poured into a solution of g. ofpoly-3,3-bis-(chloromethyl)-oxetane (of molecular weight: 170,000) in 2litres of DMSO heated to 140 C. The temperature is maintained, in anatmosphere of dry nitrogen and with stirring, for 1 hour 30 minutes.

The reaction mixture is then poured into 7 l. of Water; the product issalted out by means of sodium chloride, washed with hot water andmethanol, redissolved in refluxing tetrahydrofurane (THF), filtered,reprecipitated from boiling water, rinsed with methanol and dried.

g. of a solid are obtained which softens at about 105 C. and contains26.2% by weight of chlorine, representing a degree of phenoxylation of30%.

(C) Conversion to a screen-reinforced film.

A sheet of paper made of glass fibres having the followingcharacteristics:

thickness: 0.25 mm.

porosity: 500% (that is to say 100 g. of paper absorb 500 g. of water)and weight (g. per m. 52.5

is immersed for 15 minutes in a solution of the polyoxetane preparedunder (B) in tetrahydrofurane of concentration 60 g./l.

The product is dried for 1 hour and then this sequence of operations isrepeated. A screen-reinforced film containing intermediate phenoxylatedpolyoxetane is thus obtained.

(D) Chloromethylation.

The film prepared under (C) is immersed for 20' hours at 20 C. in thefollowing mixture:

diethyl ether: 900 cm. monochloromethyl ether: 100 cm. tintetrachloride: 10 cm.

The membrane thus obtained is washed with diethyl ether and dried at 20C. at 30 mm. Hg.

A White membrane is thus obtained having the following characteristics:density: 110.5 g./m. proportion of mobile chlorine i.e. chlorine atomswhich belong to chloromethyl groups attached to aromatic rings): 1.14meq./g., corresponding to approximately 0.125 mol/m.

The proportion of polyoxetane in the membrane is 52.5% by weight; thepolyoxetane is composed essentially of units of formula:

(E) Esterification by N-o-nitrophenylsulphenyl-D,L- valine (abbreviatedto NPS-D,L-valine) of the formula NO: C CHa (the D, L-forrn) Fiveesterification experiments are carried out in five different solvents,the common method of procedure being as follows:

438 mg. of the membrane prepared under (D) (0.5 mmol of mobile chlorine)are immersed in a solution of 135 mg. (0.5 mmol) of NPS-D,L-valine in 25cm. of solvent. After 10 minutes, 0.063 cm. of triethylamine (0.45 mmol)is added and the mixture is heated for 24 hours at 90 C. in anatmosphere of dry nitrogen. The membrane is then washed first withdioxane and then with methylene chloride.

The protective group NPS-(NO -C H -S) is then removed by immersing themembrane in a 0.2 N solution of anhydrous HCl in methylene chloride, atC.; the membrane is rinsed with methylene chloride, neutralised by a 5%solution of (C H N in methylene chloride, and washed again withmethylene chloride followed by, successively, dioxane and methanol. Aflexible membrane is thus obtained to which valine is attached via itsacid group.

(F) Determination of the aminoacid attached.

In order to determine the amount of valine attached, the valine isliberated by treating the membrane, at 100 C., in a sealed tube, for 24hours, with a mixture of equal volumes of dioxane and 6 N aqueoushydrochloric acid, and then the valine in solution is measured by meansof a Technicon automatic analyser which operates by chromatography on anion exchange resin in accordance with the method of Moore and Stein.

The following results were obtained for each of the five solvents usedduring the esterification:

EXAMPLE 2 (A) and (B) The procedure of Example 1, paragraphs (A) and(B), is followed, with the following changes: 76 g. of phenol, insteadof 58 g., and 400 cm. of methylate solution, instead of 300 cm. Theperiod for which the methylate+poly 3,3 bis-chloromethyl-oxetane mixtureis heated is 3 hours instead of 1 hour minutes.

A phenoxylated polyoxetane with a degree of phenoxylation of is thusobtained.

(C) The procedure of Example 1, paragraph (C) is followed, using asolution of the phenoxylated polyoxetane containing 100 g./l. (insteadof g./l.).

(D) The procedure of Example 1, paragraph (D) is followed.

A white membrane having the following characteristics is thus obtained:

density: 105 g./m. proportion of polymer: 50% proportion of mobilechlorine: 1.25 meq./g.

The polyoxetane consists essentially of units of the same formula as thepolyoxetane units of Example 1. (E) This membrane is esterified underthe conditions of Example 1, paragraph (E) in an acetonitrile medium, bymeans of NPS-L-phenylalanine of the formula:

o-NOzCuHiSNHCH-COOH the molar ratios employed being the same as inExample 1, and then the protective NPS group is removed as in Example 1.

A flexible membrane is thus obtained to which L-phenylalanine isattached via its acid group.

(F) Determination of the aminoacid.

In order to determine the amount of phenylalanine attached, the latteris liberated in the same way as the valine of Example 1 and it isdetermined in accordance with the technique mentioned in Example 1.

There is found to be 0.94 mmol of L-phenylalanine per g. of drymembrane.

EXAMPLE 3 (A) and (B) The procedure of Example 1, paragraphs (A) and(B), is followed.

(C) The procedure of Example 1, paragraph (C) is followed, but 4coatings are carried out instead of 2.

(D) The procedure of Example 1, paragraph (D) is followed.

A white membrane having the following characteristics is thus obtained:

density: 179 g./m. proportion of polymer: 65.8% proportion of mobilechlorine: 1.43 meq./ g.

The polyoxetane consists essentially of units of the same formula as thepolyoxetane units of Example 1.

(E) Esterification by benzyloxycarbonyl-N-glycine (BZN-glycine) of theformula:

685 mg. of membrane as prepared under (D) (corresponding to 0.98 mmol ofmobile chlorine) are heated under reflux for 24 hours in a solutionprepared from 1 mmol of BZN-glycine, 0.126 cm. of triethylamine and 60cm. of a /10 by volume dichloroethane/ethanol mixture.

The membrane is then washed with ethanol, followed by methylenechloride, followed by acetic acid.

(F) Determination of the aminoacid attached.

The ester bond is hydrolysed as in Example 1, paragraph (F), and theglycine is determined in accordance with the technique indicated inExample 1.

0.45 meq. of glycine per g. of dry membrane is measured.

EXAMPLE 4 (A) and (B) The procedure of Example 1, paragraphs (A) and(B), is followed.

(C) The procedure of Example 1, paragraph (C) is followed, but only onecoating is carried out instead of two.

(D) The procedure of Example 1, paragraph (D) is followed.

A white membrane having the following characteristics is thus obtained:

density: 67 g./m. proportion of polymer: 21.5% proportion of mobilechlorine: 0.46 meq./ g.

The polyoxetane consists essentially of units having the same formula asthose of Example 1.

(E) Attachment of N a t butoxycarbonyl N 'y benzyloxy carbonyl L 01,diamino butyric acid.

2.8 cm. of triethylamine are added to a solution of 7.05 g. of N a tbutoxycarbonyl N 'y benzyloxycarbonyl L a 'y diamino butyric acid in 100cm. of ethanol. The mixture is stirred for 3 minutes at 20 C. and thenconcentrated at 50 C. under reduced pressure (20 mm. of mercury). Theoil obtained is dissolved in a mixture of 50 cm. of ethanol and 450 cm.of dichloroethane.

4.28 g. of membrane as prepared under (D) are added to this solution.

This mixture is stirred for 54 hours at the reflux temperature,filtered, and then washed 3 times using, on each occasion, 70 cm. ofdichloroethane followed by 70 cm. of ethanol. The product is dried at 20C. under reduced pressure (0.3 mm. of mercury) and 5.1 g. ofintermediate polymer-blocked aminoacid or N a= t butyoxycarbonyl N vbenzyloxycarbonyl L 11, diaminobutyryl polymer are thus obtained, thatis to say a polymer or substratum to which N a t butoxycarbonyl N 'ybenzyloxycarbonyl L :,7 diaminobutyryl radicals are attached. Theproportion of N a t butoxycarbonyl N 'y benzyloxycarbonyl L 12,7diaminobutyric acid in this polymer is equal to 0.15 mmol/g.

(F) Attachment of N t butoxycarbonyl L threonine. The second aminoacid(N t butoxycarbonyl L- threonine) is attached by fixing the latter to g.of intermediate polymer-blocked aminoacid prepared under (E) (whichcontains 0.75 mmolof blocked aminoacid), the

N-ot-L-fi-Methyl octanoyl-N-'y-benzyloxycarbonyl-L-a, 'y-diamino-butyrylL threonyl-N-'y-benzyloxycarbonyl- L-u,'y-diamino-butyryl-"polymer isthus obtained.

(J) Isolation of the peptide thus synthesised, in the form of thehydrazide.

The polymer prepared in paragraph (H) is introduced into 100 cm. of asolution of dimethylformamide containing 20% (by volume) of hydrazinehydrate. The mixture is allowed to react, with stirring, for 17 hours at20 C. It is filtered, washed with dimethylformamide and concentrated todryness (at 55 C. 0.3 mm. Hg); the residue is taken up again in 80 cm.of water, left to stand for 1 hour at 4 C. and filtered; the insolublematerial is washed with water and then with methanol and ether. Afterdrying (20 C.; 0.3 mm. of mercury), 355 mg. ofN-a-L-6-methyl-octanoyl-N-'y-benzyloxycarbonyl- L-a,'y-diaminobutyryl Lthreonyl-N-y-benzyloxyca1'- bonyl-L-a,'y-diaminobutyryl-hydrazide areobtained.

Anulysis.Calculated: C: 59.9; H: 7.47; N: 13.21. Found: C: 60.2; H:7.65; N: 13.7.

We claim:

1. A polyoxetane which consists essentially of a plurality of units ofthe formula:

and, optionally, of units of at least one of the formulae:

CH X CHzY operations being carned out as indicated in Table (I) at 2 i 620 C.; this is followed by filtering otf except between op- (HI) I (1V)erations 6a and 6b. In the course of operation 6a of Table Hz-OAr' CHzYlI, a solution of 2.19 g. of N t butoxycarbonyl L threonine in 60 cm. ofmethylene chloride is used.

TABLE I Duration of stirring per operation in Volume of minutesOperation Number reagent in (unless or group of of operacm. perotherwise operations Reagent (or solvent) tions operation stated) Natureor purpose of the operation Acetic acid 3 60 3 Washing. 2-.. N solutionof HCl in CH3COOH 1 60 30 Removal of the group protecting the aminoradical in the a-position. 3a Acetic acid 3 60 3 Washing. 3b-. Fthanol 360 3 Do. 3c lor 3 60 3 Do. 4. 1 60 20 Neutrallsation. 5a 3 60 3 Do. 5b.-

a 60 3 Do. Methylene chloride 3 3 Do. 6a Aminoa c idtlo be attached,dissolved in methyl- 1 60 10 Mixing 01190 011 0. 6b 2.06 g. ofdicyclohexylcarbodiimide dissolved in 1 15 l 17 Condensation (attachmentof the aminoacid).

60 cm.- of methylene chloride. 7a Methylene chloride 3 60 3 Washing. 7bEthanol 3 60 3 Do.

1 Hours.

(G) Attachment of N-ot-1;-blltOXYCElIbODYl-N-y-bfillZYlandoxy-car'bonyl-L-a,'y-diamino-butyric acid.

This blocked aminoacid is attached to the polymer 60 -CH1-(E-CHOobtained at the end of paragraph (F).

CHz-O A1 The same procedure 15 used as in paragraph (F) and JIH theassociated Table (I), with the change that during 1 operation 6a asolution prepared from 60 cm. of methyl- CH2O r ene chloride and 3.52 g.of Nu-t-butoxycarbonyl-N-'ybenzyloxycarbonyl-L-a,'y-diamino-butyric acidis used. H Y

(H) Attachment of L-G-methyI-octanoic acid prepared 2 according to K.Vogler et al., Helv. Chim. Acta, 43, 279 In. which:

This acid is attached to the polymer obtained at the end of paragraph(G).

The same procedure is used as in paragraph (G) with the change thatduring operation 6a a solution of 1.58 g. of L-6-methyl-octanoic acid in60 cm. of methylene chloride is used.

each of X and X which may be identical or different,

represents a chlorine or bromine atom,

Y is as defined under X or represents a radical of formula: --OAr-CH Xor --OAr,

each of the Y radicals, which may be identical or different, representsa -0-Ar' or --OArCH X radical,

in which each of the a radicals, which may be identical or dilferent,represents a hydrogen atom or a linear or branched alkyl, alkoxy or acylradical or a nitro or nitrile group or a halogen atom, with the provisothat at most half of the a radicals are other than hydrogen, alkyl,alkoxy or acyl.

3. A polyoxyetane according to claim 2 in which a represents an alkyl,alkoxy or acyl radical with less than 7 carbon atoms or a chlorine orbromine atom.

4. A polyoxetane according to claim 1 in which Ar-- and Ar' are suchthat HArOH and ArOH represent meta-nitrophenol, 0- or m-bromophenol,guaiacol, oor m-cresol, oor m-isobutylphenol, oor m-isopropylphenol, axylenol, oor m-chlorophenol, thymol or phenol.

5. A polyoxetane according to claim 1 in which the number of groups-ArCH X expressed in milliequivalents (meq.) per gram of dry polymer, isbetwen 0.5 and 4.

6. A polyoxetane according to claim 5 in which the number of --ArCH Xgroups, expressed in milliequivalents per gram of dry polymer is between1 and 3.

7. A polyoxetane according to claim 1 in which the percentage by numberof groups -CH OAr- (including the groups CH OAr') relative to the totalnumber of substituents of the polymer chain is between 1 and 60%.

8. A polyoxetane according to claim 7 in which the percentage by numberof groups -CH -OAr relative to the total number of substituents of thepolymer chain is between 20 and 9. A polyoxetane as defined in claim 1in the form of a membrane.

References Cited Minoura et al., J. Polym. Sci., Part A-I, 5, 2843-2855(1967).

MELVIN GOLDSTEIN, Primary Examiner US. Cl. X.R.

117-126 GB, 138.8 UF; 260-1125

1. A POLYOXETANE WHICH CONSISTS ESSENTIALLY OF A PLURALITY OF UNITS OFTHE FORMULA: